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Sept. 22,..1..970 Mrrsuo KsHlzuKA 3,529,355

u COMPSSES Filed Nov. 4, 1968 2 Sheets-Sheet 1 MITSUC)` KISHIZUKA m /Tmlmxmm/ Sept. 22, 1910 M11-suo KlsHlzuKA 3,529,355

COMPASSES Filed Nov. 4, 1968 2 Sheets-Sheet 2 FlG. 5'

M|Tsuo KlsHlzuKA @www United States Patent O 3,529,355 COMPASSES i Mitsuo Kishizuka, Urawa, Japan, assignor to Kishlzuka Kikai Kogyo Kabushiki Kaisha, Tokyo, Japan, a corporation of Japan Filed Nov. 4, 1968, Ser. No. 773,246 Claims priority, application Japan, Nov. 17, 1967, 42/ 96,421 Int. Cl. B431 9/00 U.S. Cl. 33--27 3 Claims ABSTRACT OF THE DISCLOSURE The invention is directed to the structure of a pair of compasses having two spreadable legs joined at their upper ends, with one leg carrying the usual pin point but having the other leg provided with an extensible pencil device which is capable of feeding and adequately retaining therein pencil leads of extremely small diameters.

BACKGROUND OF THE INVENTION This invention relates to a pair of compasses and more particularly to pencil compasses of the type which are used in describing circles or curved lines, marking measurements, subdividing distances, and the like, and which generally involve an instrument consisting of two legs joined at the top by a pivoted joint or spring, with one leg being provided at its end with a needle point and the other leg being provided with a pencil or lead for scribing purposes, together with adjustment means for spreading or closing the legs, as desired.

In compasses of this type the legs are usually split at their ends and formed to receive the pin or needle point and pencil lead which are retained therein by means of a screw or the like, which draws the split portions of the legs together in clamping relation to thus hold the pin and lead in position. Since the pencil leads must be inserted into such a split socket clamp, the leads conventionally have been rather large in diameter in order to be properly retained therein.

In using such conventional compasses, it is difficult to draw an exact circle, because the breadth of the starting stroke will vary and differ from that of the finishing stroke due to wear of the pencil lead. It is troublesome and time consuming to have to repeatedly interrupt use of the compass to sharpen the pencil lead in order to secure a constantly fine stroke.

Recently, thin pencil leads of less than 0.8 mm. in diameter have appeared on the market. The conventional compasses have been found to be inadequate and incapable of holding such line leads.

SUMMARY OF THE INVENTION The primary object of this invention is to provide a pair of compasses equipped with an extensible pencil device which can reliably and securely hold a ne pencil stick or lead, even a lead of such small diameter as 0.8 mm. or less.

A second object of this invention is to provide a pair of compasses equipped with an extensible pencil device which permits a stick of lead to be easily inserted or removed therefrom.

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A further object of this invention is to provide a pair of compasses equipped with an extensible pencil device which permits leads of different diameters to be mounted freely and easily by simply changing the pencil tips or caps.

An additional object of this invention is to provide a pair of compasses equipped with an extensible pencil device employing a structure which provides shock-resistant means for supporting the lead-holding tubular member of the pencil device.

Other and further objects and advantages of the present invention will become apparent from the following description and the appended claims, reference being had to the accompanying drawings forming a part of this specication. The invention may be embodied in the form illustrated in the drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific constructions illustrated and described, so long as the scope of the appended claims is not violated.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings which form a part of this application:

FIG. 1 shows in front elevation a compass, or pair of compasses constructed in accordance with this invention;

FIG. 2 shows the compasses in side elevation as viewed from the right side of FIG. l;

FIG. 3 shows a side view of the extensible pencil device detached from the compass leg;

FIG. 4 shows in front elevation another embodiment of this invention; and

FIG. 5 shows an enlarged detailed section taken along the line V-V of FIG. 3.

Like characters of reference are used throughout the following specification and the accompanying drawings to designate corresponding parts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As indicated in FIGS. l to 3, a pair of compasses 1 according to this invention consists of two legs which are pivotally joined at their upper ends and freely openable, one of said legs being equipped with a needle point and the other leg 1a having a detachable extensible pencil device, which, as seen in FIG. 4, may be consolidated or made integral, if desired, with the leg 1a.

As illustrated in detail in FIG. 5, said extensible pencil device includes a hollow pencil lead-holder 2 which is open at its outer end for the reception of the lead feeding mechanism to be hereinafter described. The outer end of the holder 2 is internally threaded at 3 to receive an externally threaded bushing means 4 which completely supports and fixes the pencil lead feeding mechanism in the holder 2.

The bushing means 4 is provided with an internal shoulder forming a large diameter bore part 4a and a small diameter bore part 4b. Within the large diameter bore part 4a is xed one end of a threaded guide member 5 provided with a spiral or threaded groove 5a, the guide member 5 being adapted to extend within the hollow holder 2 and be supported therein by said bushing means 4 as shown in the drawings.

Inside the threaded guide member is inserted a leadholding tubular member 7 provided with a guide groove or slot I6 extending longitudinally along one side surface. The upper end of said tubular member 7 extends beyond the upper end of the threaded guide 5 and has fixed in any mannner thereto a stop member 8, which engages or bears against the top end of the threaded guide S and prevents the lead-holding tubular member 7 from slipping out of the threaded guide member 5. The lower end of the lead-holding tubular member 7 extends through and is laterally supported within the small diameter bore part 4b of the bushing means 4 whereby shock transmission to the lead-holding tube is prevented or reduced to a minimum. The lower outer end of the lead-holding tubular member 7 beneath the bushing 4 has xed thereto, or formed integral therewith, an enlarged diameter rotatable part 9, which in turn5 is formed with a reduced externally threaded stem portion 10 for the reception of a detachable cap or pencil tip 11 screwed thereon.

Inside the lead-holding tubular member 7 is loosely inserted a tapered lead-stop and follower member 12 of gradually decreasing diameter, as shown. One side surface of this lead-stop is cut longitudinally to provide a groove 13 therein, along one portion of which is fixed a sliding piece or ear 14. Also out of said longitudinal groove 13 extends a sliding piece 16 of L-shaped configuration and forming a downwardly extending push or ejector pin 15, said pin centered within the lead-stop 12, as shown in FIG. 5.

The sliding pieces 14 and 16 extend radially outward through the guide groove 6, to engage the spiral groove 5a of the threaded guide member 5 and hence on rotation of tubular member 7 with reference to the fixed or stationary guide member 5, pieces 14 and 16 will follow or track in the groove 5a.

The end of a pencil lead 17 is inserted by hand through the cap or tip 11 and is pushed inwardly until its upper end fits snugly into the conical or tapered lead-stop 12 which securely retains the lead in position in the pencil device. Preferably, a bearing or washer 18 is disposed between the threaded bushing means 4 and the rotatable part 9 of the lead-holding tubular member 7.

By virtue of the construction of this embodiment of the invention, as described, the lead-holding tubular member 7 and the cap or tip 11 can be rotated by manually turning the rotatable part 9 by the fingers. Upon such rotation, the lead-stop or follower 12 will turn with the tubular member 7 and in the same direction since the sliding pieces 14 and 16 project through the vertical guide groove -6 of tubular member 7. At the same time, since the sliding pieces 14 and 16 also engage the spiral groove Sa, and the guide 5 is fixed, the lead-stop or follower 12 will smoothly move vertically up or down with in the tube 7 and along the thread of the threaded `guide member 5. By virtue of this vertical movement, the pencil lead 17 will be fed out of the tip of the cap 11 or retracted within the device, as desired, depending upon the direction of rotation of part 9.

When the pencil lead has been substantially depleted in use and must be replaced by a new lead, the remaining portion of the old lead 17 can be removed from the pencil device by means of the ejector-pin 15 since only the sliding piece 16 is movable vertically along the long groove 13 in the lead-stop or follower 12. Since the sliding piece 14 is fixed to the lead-stop and follower 12 the latter will be Varrested in its downward movement in the lead tube 7 when the piece 14 reaches the end of the thread groove 5a and/or the follower abuts the part 9. When downward movement of the tapered follower has been so stopped, further rotation of the part 9 will result in the sliding piece 16 continuing its downward movement relative to the follower and ejector pin 15 will force the inner end of the remaining lead out of its frictional fit in the tapered follower. After the old lead has been removed, a new pencil. lead 17 may be inserted 4 through the tip of the cap 11 into the lead-stop 12, and by forcefully pushing the lead inwardly it will be reliably gripped in the tapered socket portion of the stop 12.

It will be noted that the entire pencil lead feeding device including its tip can easily be removed as a unit from the holder 2 by merely unscrewing the bushing means 4 and withdrawing the mechanism from the holder.

In the embodiments disclosed the threaded guide tube 5 is illustrated as one having a wide pitch of thread, however it is not necessarily confined to such a construction, since the guide 5 may be formed as a linear coil spring.

If there is no need for the sliding piece 16 and its ejector pin to push out the pencil lead 17, the sliding piece 14 alone will suiiice and in that case the lead 17 merely has only to be pulled out of the lead-stop or follower 12 when it is to be replaced with a new lead.

Such being the construction and function of the embodiments of this invention, it will be undestood that the major portion of the lead, except for its writing tip, 1s contained inside the cap 11 and the holder 2, and accordingly there is litttle likelihood of the lead being accidentally broken in use. Furthermore, when not being used, the entire lead may be completely withdrawn, so there is no danger of the lead being broken. Nor is there any possibility of the lead being broken at the point of support since it is not held tightly at a midpoint as is the case with the leads used in conventional Compasses.

The outward feeding and the retraction of the pencil lead 17 is easily accomplished by merely turning the rotatable part 9 and use of a long lead is permittted. The tapered form of the lead-stop 12 permits the holding of leads of different diameters, large and small. Therefore, a Variety of pencil leads can be used in this device, if several t1ps or caps 11 are provided with differently sized lead openings corresponding to the desired lead diameter.

While the present invention has been explained and described with reference to specific embodiments of structure, it will be understood, nevertheless, that numerous modifications and variations are susceptible of being incorporated without departure from the essential spirit or scope thereof. Accordingly, it is not intended for an understanding of this invention to be limited by the foregoing description nor by the illustrations in the annexed drawings, except as indicated in the hereinafter appended claims.

What is claimed is:

1. A pair of Compasses composed of two freely openable legs, one of said legs having attached thereto at its outer end a needle point and the other leg being equipped with an extensible pencil device, said pencil device comprising a hollow lead-holder open at its outer end, a threaded guide member provided with a thread groove and disposed within the hollow portion of said lead-holder and fixed thereto, a lead-holding tubular member disposed within said threaded guide and provided with a groove extending down one side surface, a lead-stop and follower freely slidable within said tubular member and provided with means for guiding the same along the groove of said threaded guide and the groove of said tubular member, said lead-stop and follower having a tapered configuration increasing in diameter towards the tip end of said device and provided with a groove extending through one side thereof, and a rotatable part fixed to said tubular member and positioned at the outer end of said holder by which said lead-holding tubular member may be turned in relation to said threaded guide member.

2. A pair of Compasses as defined in claim 1, wherein said lead-stop and follower is provided with a lead ejector pin, said pin having a sliding piece extending through the groove in said lead-stop and follower and the groove of said tubular member and engaging the thread groove of said threaded guide member, said pin adapted to push 5 the lead out of said lead-stop and follower when the latter reaches the outer tip end of said pencil device.

3. A pair of compasses as defined in claim 1, wherein said hollow lead-holder is provided with a bushing means at is outer end, said bushing means having a larger diam- 5 eter bore portion and a small diameter bore portion, with said threaded guide member having its lower end portion fitted and fixed to said large diameter bore portion References Cited UNITED STATES PATENTS 2,110,551 3/1938 Friedlein et al. 120--18 2,573,760 1l/1951 Cherne 33-27 FOREIGN PATENTS 424,707 2/ 1935 Great Britain.

LEONARD FORMAN, Primary Examiner lo C. E. PHILLIPS, Assistant Examiner 

